I recently had to help a person who was having problems seeding a torrent. After a lot of examination, I suggested he change his port range, and suddenly he was able to upload on remotely-initiated connections. Apparently his ISP was throttling his upstream on BT connections to nearly zero.

This is a serious development that affects the BitTorrent protocol's ability to function, and steps need to be taken to fix it.

I recommend all of you change your BT port range to a block of approx. 20 ports over 10000 but below 60000. Here's an example; min port 32681, max port 32699. Don't use this example, but instead choose your own range; if a lot of people use a particular range, that range may be targeted as well.

Future versions of BitTornado will have an option to choose its port in the available range randomly rather than searching linearly, and this option will be enabled by default. IF YOU CURRENTLY HAVE PORTS FORWARDED, YOU MAY NEED TO CHANGE YOUR PORT RANGE AND/OR FIREWALL SETTINGS TO ACCOMMODATE THIS CHANGE. The default port range on new installations will also be changed to a wide block of high-range ports.

Why this change will help:

BitTornado, and AFAIK most BitTorrent clients, open outbound connections using the standard temporary range (1024-5000), so an outbound BT connection can't be determined just from that port. The peer it connects to may still be using the standard 688x range, which would mean your ISP could isolate and throttle those connections. If your server port is opened on a non-standard port, and a client initiating a connection to you is using a port in its temporary range, then your ISP won't be able to determine whether the connection is for BitTorrent unless it monitors the protocol handshake.

I would have thought everyone using Bittorrent was already aware of this but it appears not.

Most of the ratio implemented torrent sites already blacklist the default port ranges and have been doing so for quite some time.
From the FAQ of one such site.

Code:

Why do I get a "rejected by tracker - Port xxxx is blacklisted" error?

Your client is reporting to the tracker that it uses one of the default bittorrent ports (6881-6889) or any other common p2p port for incoming connections.

********** does not allow clients to use ports commonly associated with p2p protocols. The reason for this is that it is a common practice for ISPs to throttle those ports (that is, limit the bandwidth, hence the speed).

The blocked ports list include, but is not necessarily limited to, the following:

In order to use use our tracker you must configure your client to use any port range that does not contain those ports (a range within the region 49152 through 65535 is preferable, cf. IANA). The size of the range you choose should take this into account (typically less than 10 ports wide. There is no benefit whatsoever in choosing a wide range, and there are possible security implications). These ports are used for connections between peers, not client to tracker. Therefore this change will not interfere with your ability to use other trackers (in fact it should increase your speed with torrents from any tracker, not just ours). Your client will also still be able to connect to peers that are using the standard ports. If your client does not allow custom ports to be used, you will have to switch to one that does.

Do not ask us, or in the forums, which ports you should choose. The more random the choice is the harder it will be for ISPs to catch on to us and start limiting speeds on the ports we use. If we simply define another range ISPs will start throttling that range also.

iptables and ipp2p patch seem to work no matter what ports p2p aplication is functioning. Patches are developed as well as BT so it would be difficult to overcome this problem. (I am a network administrator)

Those probably read the packets though. For an ISP, it's too infeasable to read every single packet and figure out what is what. And no ISP would use Linux for its core routing. No serious ISP anyways.

Those probably read the packets though. For an ISP, it's too infeasable to read every single packet and figure out what is what. And no ISP would use Linux for its core routing. No serious ISP anyways.

I am from Poland. There is no serious ISP the company I am working in is providing Internet in one city and its surroundings, so it's rather small linux is doing fine as for OS on routers

Its really sad that isps do this, I don't see the problem with their customers actually using the full speed of their connections, as advertised, that they pay for..

I'm sure most isps would make the excuse about illegal software downloads (although that could be made for *any* aspect of the internet) and ignore all of the good uses like downloading linux isos and game demos (both of which I do..). :\

Future versions of BitTornado will have an option to choose its port in the available range randomly rather than searching linearly, and this option will be enabled by default. IF YOU CURRENTLY HAVE PORTS FORWARDED, YOU MAY NEED TO CHANGE YOUR PORT RANGE AND/OR FIREWALL SETTINGS TO ACCOMMODATE THIS CHANGE. The default port range on new installations will also be changed to a wide block of high-range ports.

I hope it would be a small change because I am using ISA 2000 firewall.
I have to manually forward ports ONE at a time.

I hope it would be a small change because I am using ISA 2000 firewall.I have to manually forward ports ONE at a time.

Shad0w was way ahead of you.

The selection is limited to the range of ports you set on the Prefs screen, so you can set it to a range of, say, twenty consecutive ports, forward those, and let BitTornado pick among them. Â If that doesn't work out, you can always uncheck the "randomize" box on the Prefs screen and get things back as they used to be.

BitTorrent has no fixed port it contacts. There's a high probability it will connect to at least one client on port 6881, but because of this throttling problem that probability may decrease in the future. I'm sorry but you may have problems port-forwarding with that router in a few months.

I can understand ISPs wishing to throttle BT traffic, but throttling to zero is just wrong.